temp alarm for suzuki df115

[kiwiflya]

Hi guys have been having an issue with a temp alarm at idle only after 20 minute steam.

Boat runs fine at high rpm but within a minute or two at idle afterwards a temp alarm sounds on dash and motor cuts out.

Thermostat operating ok, tell tale looks ok, poppet valve clear, sensors in good condition.
Serial
number
DF115
1501F-683054


Only thing odd i noticed was the water plug which appeared melted or somewhat damaged

[boats.net]

May need to replace water pump.

[kiwiflya]

I have had heat alarms in the past but usually the motor goes into guardian mode, not just dead cut then beeping temp alarm.